As microprocessors become faster, the need for faster memory interconnects increases. Microprocessor performance has increased dramatically. System performance has generally not kept pace with the increased performance of microprocessors due to a variety of reasons. One reason is the mechanical nature of mass storage devices such as hard disk drives.
Another area affecting system performance is memory external to the microprocessor. This memory may consist of both external high-speed cache and external generally lower speed, but larger in size, main memory. Accesses to external memory may have latency and implementation complexity that affect performance. The ability to reduce latency and reduce implementation complexity is beneficial. A protocol with optimizations for interconnecting with a memory is also beneficial.